Can I just dump?

You do not have to have "solid" footing to extend the slides. As long as the site you are on is level enough for comfort, you can extend the slides. 20 years ago when slides made their appearance, very few Motorhomes had Jacks. BUT, Dealers and OEM's found out that when on the dealers lot and the slides were extended, the RV's leaned to the slide out side and were NOT level enough and looked horrible. So, they started installing Jacks as standard equipment on Motorhomes with slides. Others did the same because MOST buyers wanted the Jacks and be able to level the motorhomes. Somewhere, because some OEM's state to level then deploy the jacks AND others state to deploy the slides and then level, people got the idea that NO jacks was a BAD thing when deploying the slide rooms. Not so. Now, if the chassis is obviously twisted due to holes or extremely uneven ground, then extending the slides would not be a good idea. I NEVER deploy jacks when extending the Rooms in our shop. Been doing that for almost 25 years and all brands and models of RV's and motorhomes. NEVER had a problem. Never have I seen a complaint on any forum about a RV'er that stated he extended his rooms without the jacks and something jammed or broke due to NO JACKS. IOW, he was told his slide problem was directly caused by no jacks extended. Doug